Table 1.

Outcome of Selection of Friend Control Fathers for 199 Case Fathers in a Case-control Study of Retinoblastoma, United States, 2002 – 2007

	Any control
	#	%
Total cases	199	100
At least 1 control interviewed	137	69
Case did not nominate control and provide correct contact information	36	18
Case declined to nominate control	7	4
Case had no eligible friend	17	9
Case nominated control but never provided contact information	11	6
Case provided Incorrect contact information	1	1
Contacted control did not participate	26	13
Control ineligible	2	1
Control refused	13	7
Father’s interview not completed before study ended	11	6